It has been quite some time since I posted here - work, family, and side projects have kept me busy. I'm also working to get my consulting business off the ground and I already have a couple of clients that I am doing some Form 4 packages for. One of my most recent projects though was to explore some ideas for LED lighting for steam locomotives.

Working with a custom lighting manufacturer, I've had a small production run of 34V DC LED light bulbs made. These bulbs are designed to be direct replacements for the small 15W incandescent bulbs used in illuminating gauges, water glasses, and number boards. They have the standard E27 base so there is no modification of the socket required. They turned out being a bit brighter than the 15W bulbs, but the color temperature is between 2600-3000K which mimics the softer glow of an incandescent bulb and makes the light less harsh. They are intended to be used with 34V systems but should perform well over the range of 30V to 36V.

I have only a small number of the bulbs remaining and I've decided I'd like a good cross section of locomotive operators to try these out. I'm going to make these available to the first 5 people/organizations who contact me via PM. All I ask is that you put them in service and then get back to me with some feedback about their performance. If people find them satisfactory I'll have a larger run produced and I'll make them available to the entire preservation community.

Talk to the traction people too. They use 32V bulbs and have been chewing nails over sourcing. Particularly in PCCs, which use dozens of them, and most are behind a dome so the LEDyness won't be so apparent.

I trust you understand that the majority of LED bulbs have a switching regulator, which works fine on a wide variety of input voltages. (this doesn't work if the regulation is simply resistors.)

Most likely, your bulbs are already designed to work on a range of voltages - for instance my 12V Edison-base bulbs work on 12 or 24 volts "nameplate" and will probably run on 32V as well. I'm assuming they put more robust components in one of those designs; the upper limit on voltage is only insulation strength.

If your bulb can go as low as 12V, that opens you to the RV, solar and caboose market, which use 12-24v and Edison bases.

If your bulb can go as high as 74v, that opens you to the vast diesel locomotive market as well as many passenger coaches.

12-36v or 32-74v are perfectly achievable ranges. 12-74v might be a bit ambitious.

I am pleased to see the response from my original post - all of the remaining bulbs are spoken for and I will be mailing them out early next week. I would still like to hear from people who might be interested in trying them out though. If I get enough of a response and if I get good feedback from those that will be testing the bulbs, I'll proceed with a full run of bulbs.

I would want to test them first, but the bulbs should be good up to around 42V. When we designed the driver, we used a 42V IC and a 50V capacitor. I haven't looked at other voltages, but 12, 24, and 32V versions would be easily achievable. In my research I've found bulbs in the 20-95V range but these seem to be meant for new installations or retrofitting an existing fixture. I'll investigate this further and see what my manufacturer's capabilities are.

Paul Class of Willits, CA has had bulbs made for PCC as well as streetcar needs. Check him out for quantities and availability. Paul183@instawave.net

Besides posting here you might also contact the Association of Tourist Railroads and Railway Museums and ask them to spread the word. ATRRM is the recent combination of TRAIN and ARM.

Another potential market is in the boating industry. We've started some research into sources for 32v lamps for locomotive use and found them in the boating world. There are 15w and 40w equivalent lamps which is what we were thinking for gauge glass lamps(15) and classification/number board lamps (40). Mid-Continent would at least be interested in hearing about your progress.

mld

I'd like to add a little bit to this thread. I work for a Class 1. As you know, all the step lights, number board lights, walkway lights and those over the trucks themselves on locomotives are gradually being replaced with LED lamps. The severe duty incandescent lamps are about all gone.

A fellow I know was provided a whole case of these new LED lamps by a retiring locomotive shop electrician. He decided to replace all the florescent lamps in his large shop with these LED lamps. He is quite the experimenter, and a electronics guru.

At first he was going under the assumption that since they locos' were 74 volt systems, that's what he needed to operate these. I gave him a 110vac to 74vac transformer I had so he could use it for his lighting system.

Then, he did a little experimenting. Turns out, these new bulbs will operate down as low as 24 volts, and will run on either AC or DC- with no detectable loss of intensity or noticeable flickering.

One little 24vac doorbell transformer will run this whole shop full of LED lamps. Bright white light on pennies a day of electricity. They have the regular screw in (Edison ?) base, so all he had to do was come up with the appropriate number of bulb base sockets.

I've been thinking a lot about using waste heat to generate electricity on steam locomotives rather than using steam inefficiently in a dynamo (eliminates that whining noise also) and low power consumption lamps would certainly help. 24 volt truck lamps were readily available, but sounds like these made for lower voltage like 24DC might be even more useful since no alteration of the fixtures would be required. Please do continue with your development - it could be very useful.

dave

I currently carry 32V LED bulbs. These bulbs were tested in 2013 on the NKP 765. As stated in the earlier post the feedback I received was that they were brighter than the bulbs they replaced.

Tech Specs:
Warm White
Voltage: 22-39 Volts DC
Watts: 3
Amps: 0.125
Lumens: 240
Dimensions (tip to tip): INCHES: 2 3/4 x 1 3/4

I have access to a variety of LED bulbs in Voltages from 12 to 75VDC. If interestd send me a PM or contact me at sales@evansgroup.net

The new 100W LEDS work at 34 volts and put out thousands of lumen https://www.youtube.com/watch?v=pWGX3HVb_zc

One thing to keep in mind for the traction community is that these LED lamps may not work, as is, in the typical series circuit. The tiny circuit board inside the base of the lamp would have to be specifically designed for this service. In particular, when the switch is first turned on, before any current flows, there is 600 volts open-circuit potential across _each_ bulb. This might fry some marginally designed component, such as the input rectifier. Then there might be problems with getting the string started up and getting all the voltages equalized. The LED circuits are not ohmic loads. Harmonic interaction between the switchmode converter inside the lamp and the 360Hz or 720Hz ripple typically seen in rectified 600V DC line is another consideration.

Operation from a 600V trolley requires more attention to lightning protection. LEDs are very sensitive to surge.

Things are much friendlier when you are talking about a 32 or 74 volt battery bulb. The presence of the battery helps to smooth out any ripple that might be present if you have a solid state converter, and of course if the battery is fed by an MG or a dynamo then even better.

"PCC" bulbs are 30 volts designed to operate in strings of 20. The same applies with regard to the open-circuit voltage and the startup problems. The original bulbs are also designed to fail shorted. This might not be an issue because of the longer expected lifetime of LED lamps.

As a preservationist, I find the suggestion of using LED or other modern lighting technology in antique streetcars abhorrent. It might be another story in "heritage" railway operations or where the cars are subject to heavy real-life transit system use. Museums are supposed to be preserving the entire experience and technological history, not just a box with a nice paint job that runs. This includes the motors, brakes, seats, doors and lights. If there comes a time in the future when incandescent lamps are unobtainable (as opposed to just a little bit more expensive) then something else would have to be found. But I think these bulbs will continue to be made, albeit a niche industry, just as you can still get a variety of films, vacuum tubes and other obsolete technology.

Not to hijack this discussion too badly, but since 100W 32 VDC bulbs were mentioned, does anyone know where to find 200W 64-72 VDC Edison based headlight bulbs? Either Incandescent or LED.

Thanks
Rich C.

For whatever its worth I can report that we've been using LED bulbs on Baldwin 2-8-0 # 40 at the NH&I for a couple of years in the cab for the gauge lights and they work well and hold up good.

The light is a good deal better than the older bulbs.

Ross Rowland

Rich,

I have 250W 32VDC Edison based (E26) locomotive headlight bulbs in stock. I can check with my suppliers and see about the 200W 64-72VDC if you'd like.

Nate

It appears that Nate is a little further ahead of me in the research department, but there's nothing wrong with a little bit of friendly competition is there? I think our goals are the same though - to provide a quality product to the preservation industry and to help keep these marvelous machines going for future generations to enjoy.

I had the opportunity to test the bulbs this past weekend on the PM 1225 with some mixed success. One of the dyno's over-rev'd and the power surge blew out the driver circuit. The LED's themselves weren't damaged, and so with the few spare components I had on hand and a few minutes with the soldering iron we were back in business. The improved circuit performed well and the test bulbs were still burning brightly at the end of the day.

I'll be talking to my manufacturer later in the week to discuss some design changes and to see about having another small batch produced. I'll also have the chance to discuss some of the various requests I've received via PM or the suggestions seen above. In fact, since I do have this opportunity, I'd like to get together a "wish" list of the various types of bulbs that we'd all like to see produced. If you can provide me any information at all (voltage, wattage, base style, size, part number, etc), I'll explore my manufacturers capabilities.

Thanks to everyone who contributed to this conversation.